Complete the indicated task to obtain the corresponding mask, in order of appearance.

Unlockable	How to unlock
Aubrey (Pig)	Complete Chapter 2 "Overdose" with a high score.
Brandon (Panther)	Complete Chapter 17 "Fun & Games" with a high score.
Carl (Grasshopper)	In Chapter 8 "Push It ", search the corpse on the ground level in the center room.
Charlie (Octopus)	Found on the counter in the kitchen area in the northwest of Chapter 16 "Safehouse". You must first clear the level and to talk to the owner before it can be obtained.
Dennis (Wolf)	Complete Chapter 5 "Full House" with a high score.
Don Juan (Horse)	Complete Chapter 3 "Decadence" with a high score.
Earl (Walrus)	Search the corpse in the south green room on the second floor of Chapter 2 "Overdose".
George (Giraffe)	Complete Chapter 6 "Clean Hit" with a high score.
Graham (Rabbit)	Complete Chapter 4 "Tension" with a high score.
Jake (Cobra)	Search the corpse in the northwest section of Chapter 10 "Hot & Heavy".
Jones (Alligator)	Reach the end of Chapter 5 "Full House", then get a crowbar and go to the entrance of the level. Do not go in the car. Instead of that, walk around the house until you find a manhole located at the southeast corner of the level. Enter the manhole to find the mask next to a corpse in the sewers.
Louie (Chameleon)	Complete the game with the normal ending
Nigel (Bat)	Complete the game with the alternate ending.
Oscar (Mole)	Complete Chapter 14 "Vengeance" with a high score.
Peter (Unicorn)	Complete Chapter 11 "Deadline" with a high score.
Phil (Fish)	Talk to the janitors in Chapter 19 "Resolution" then search for a box in the sewers.
Rami (Camel)	Complete Chapter 9 "Crackdown" with a high score.
Rasmus (Owl)	Complete Prelude "The Metro" with a high score.
Richard (Rooster)	Start the game.
Richter (Rat)	In Chapter 13 "Assault ", search the uppermost room of the final level (where you fight the barricaded Police Chief)
Rick (Fox)	Complete Chapter 16 "Safehouse" with a high score.
Rufus (Elephant)	Complete Chapter 8 "Push It" with a high score.
Ted (Dog)	Complete Chapter 7 "Neighbors" with a high score.
Tony (Tiger)	Complete Chapter 1 "No Talk" with a high score.
Willem (Monkey)	Complete Chapter 10 "Hot & Heavy" with a high score.
Zack (Frog)	Complete Chapter 13 "Assault" with a high score.